The present invention relates to a method of cleaning factories manufacturing LSIs or VLSIs, factories manufacturing biopharmaceuticals, surgical operating rooms, precision machinery-washing factories and factories manufacturing sterile food, or objects placed in these factories and rooms, as well as the operatives, patients and the like therein wearing clothes.
More particularly, the invention pertains to a method wherein air, containing 2,000,000 mist particles or more of essentially not more than 0.5 micron per cubic feet, is sent to VLSI-manufacturing factories, sterile food-manufacturing factories, air-shower rooms in these factories into which operatives go before the commencement of work, or the sickrooms of seriously ill patients, to clean objects.
In general, hospitals, pharmaceutical-manufacturing factories, laboratories and so forth require a clean atmosphere containing no dust or microbes. Therefore, a means is employed such that air is cleaned by the use of an air filter or an air curtain is installed at the entrances and exists thereof. However, these means cannot provide a sufficiently cleaned gas, and the employment of an air-shower room still cannot attain the purpose of providing such a clean gas.
The present inventor has found, as one result of a zealous study into the cleaning of objects, that the smaller a waterdrop, the lower its surface tension and that when a waterdrop becomes a mist particle of 0.5 micron or less, it adheres strongly to microscopic objects, and, moreover, if a gas containing 2,000,000 or more such mist particles per cubic feet is applied to an object, the gas adheres not only to microscopic dust, but also to viruses as well as bacteria, mold fungi, and spores present therein and carries them away, thereby allowing the object to be cleaned. Moreover, it has been found that a gaseous atmosphere in which such microscopic waterdrops are suspended can clean the atmosphere as well as offer such the unexpected advantageous effect that although there are waterdrops present, the object will never be wetted even if the number of mist particles is larte, provided that each of the mist particles is essentially not more than 0.5 micron. It has also been found, as the result of further examinations, that when an ordinary gas is passed through a gaseous atmosphere in which are suspended microscopic water drops, the ordinary gas is highly cleaned so that it is ultraclean, and such a highly cleaned gas can be directly applied to various rooms, sections and other related places. The present invention has been completed on the basis of this new knowledge, and as the result of the repetition of various experiments and researches concerning, in particular, an industrially effective method of producing a gas in which are suspended microscopic waterdrops.